This invention relates to a zero insertion force test socket for leadless chip carriers and, more particularly, to a test socket that permits the automatic insertion and removal of leadless chip carriers for electrical test and vertification.
Leadless chip carriers are very tiny components having a pattern of minute connection terminals thereon, as well as having minute identification markings thereon. Due to this miniature nature of the component, errors have been made frequently in installing them into the apparatus in which they are used. Sometimes the wrong component is installed; somtimes the component is oriented incorrectly; and sometimes the component is electrically imperfect as to its characteristics or operation. Rework and replacement is costly and time-consuming, and should be reduced or eliminated.
Accordingly, it was deemed desirable to test and verify the leadless chip carriers prior to their being soldered into the apparatus. It was considered desirable to be able to automatically insert and remove the leadless chip carriers into a holder or test socket at a station along the assembly line just prior to the soldering operation for testing and verification.
The only available sockets require either considerable force to insert or remove the leadless chip carrier due to the resistance created by side-wiping spring contacts, or a mechanical holding or clamping device.
In the past, there were no sockets in which leadless chip carriers could be automatically loaded and unloaded. The closest socket to the test socket 10 of the present invention is the LOCKNEST socket made by Plastronics, Inc. (not shown). The LOCKNEST socket is loaded by pressing down on the top of the socket, which retracts mechanical contacts. After the leadless chip carrier is inserted, pressure is released from the socket and the mechanical contacts "lock onto" the leadless chip carrier. To unload the socket, pressure is again applied to the top of the socket, and a blunt instrument is used to push the leadless chip carrier out from the bottom.